Modified fluid coking process



Oct 11, 1956 J. w. BROWN MODIFIED FLUID COKING PROCESS Filed June 26, 1965 PATENT ATTORNEY United States Patent ice 3,278,412 Patented oct. 11, 1966 3,278,412 MODIFIED FLUID COKING PROCESS .lames W. Brown, Westfield, NJ., assignor to Esso Research and Engineering Company, a corporation of Delaware Filed June 26, 1963, Ser. No. 290,763 5 Claims. (Cl. 208-11) This invention relates to an improved process for the recovery of hydrocarbon oil from bituminous or tar sands or the like in which the oil is in admixture with mineral solids and water. More particularly, this invention relates to a modified system of iiuid coking in which viscous crudey petroleum oil is separated and cracked from a mixture with sand, clay and Water.

In various areas of the world, tar sands exist which contain various types of hydrocarbons as, for example, the large deposits of Athabasca tar sands existing in Canada. These sands contain tremendous reserves of hydrocarbon constituents. For example, the oil in the sands may vary from about 5% to 21% by volume, generally in the range of about 12% by volume. The gravity of the oil ranges from about 6 to 10 API, generally about 8 API. These sands may lie from about 200 to 300 feet below an overburden and the beds may range from about 100 to 400 feet thick. A typical oil recovered from the sands has an initial boiling point of about 300 F., 1.0% distilled to 430 F., 20.0% distilled to 650 F. and 50.0% distilled to 980 F. However, the recovery and processing of hydrocarbons in the past has not been effective to any great extent due to the deficiencies in operating techniques for the recovery of these hydrocarbons. For example, relatively small amounts of fine clay and sand (from about 0% to 30%, usually about 5%) may result in formations of a stable emulsion containing sand, clay, water and bitumen which is apparently stabilized by the ine solids. This makes further processing by conventional techniques exceedingly diliicult.

Numerous attempts have been made in the past to recover bitumen from the Athabasca tar sands in various manners. For example, it has been suggested that a solvent beadded in order to reduce the viscosity of the bitumen, and in conjunction with water, to float the bitumen solvent mixture away from the sand. Although this technique achieves a good separation of clean sand, the addition of water results in problems with the formation of stable emulsions and sludges which have been very diiiicult to separate. Thus, extensive supplementary processing has been required in order to avoid large losses of oil and solvent.

It has also been suggested in the past that tar sands as they are mined be handled by a thermal process in order to recover the bitumen therefrom. However, this process has been uneconomical due to the large amount of heat which is lost due to the fact that the heat is imparted to the sand and cannot be effectively and eliiciently recovered therefrom. It has been suggested for example that tar sands be handled in a direct iluid coking operation. However, as pointed out, this process is uneconomical for the reasons given above. Also, any process that will effectively handle tar sands must have the ability to handle a very wide range of tar sand and compositions which occur even in an immediate location. Underground extraction with hot water is currently being carried on but this has met with limited success.

Further problems have been encountered from fine clay and sand in the tar sands when attempting to separate oil by means of a fluid coking process. Fine clay particles may be carried to the scrubber by entrainment in the vaporous hydrocarbon product and once there either completely clog the scrubber or greatly reduce its eiiiciency.

Alternatively, fine material and other solids may be released through the stack in the burner. With large scale operations such as would be undertaken in the Athabasca region this would .amount to several tons of material per day and have a most unsatisfactory efect on the surrounding area.

Tar sands contain between about 3 and 20 Wt. percent crude oil and between about 1 and 10 wt. percent of water. Sand and other mineral matter, i.e. clay, form about to wt. percent of the tar sands. About 1-20% of this mineral material is fine material.

According to a preferred embodiment of this invention, a tar sand which may be lan Athabasca tar sand is subjected to a froth flotation. That is to say, hot water is mixed with the tar sand; several phases are formed including an aqueous phase, a sand phase, and a froth. The froth forms because gas is liberated from the bitumen, the gas being predominantly ethane, methane and trapped air. The froth may contain up to 40 vol. percent of gas. The water phase and the sand phase are withdrawn and discarded.

This froth is then subjected to a iiuid coking process to remove oil and water and to form coke and lower boiling hydrocarbons from the oil Within the froth. Extraneous hot gas or fuel may be added to the burner of the coking unit and this combined with the low coking temperature utilized prevents the coke from being entirely burned to provide heat for the coking process. The lighter overhead hydrocarbon products are separated from the heavier products and removed or may further be put to use, as will subsequently be explained. The heavier, 900 F.|- fraction, is subjected to conventional process such as fluid coking in which gas and liquid product are produced along with a high value coke. However, the heavier fraction may be subjected to other processes such as visbreaking, for example.

The solids, including sand and other mineral matter such as clay, are coated with coke in the iirst stage, low severity or low temperature coking reactor during the coking step, and the coated solids are then trapped within the coking reactor. By trapped it is meant that the coke coating serves as a glue. Therefore, the smaller solids become stuck to larger particles and this serves to keep the smaller solids within the reactor rather than allowing them to escape through the stack. This is particularly true of very line solid material within the l to 5 micron range; the cohesive force of the coke tends t0 keep them stuck to larger particles and, therefore, they tend to remain within the coking unit. As much as 50% of the coke formed during coking is maintained on the solids.

Fines from the cyclones of the low temperature burner together with some of the coarser solids from the burner are regenerated in a iiuid bed and used as cracking catalyst in the reactor. The clay in these particles becomes activated and acts as a cracking catalyst. Some of the stack solids from the high temperature burner may also be used for this purpose.

The net carbon or coke coated solids are removed from the burner of the fluid coker and are introduced into a relatively high temperature burner. Because of the high temperature in this burner, and the fact that all the coke is burned, the coke coating is burned to CO2 thereby producing a llarge amount of heat. This heat in the form of hot gas is passed into a boiler where it may be utilized for the production of steam. Alternately, part of this hot gas may be passed through the coker burner to supply heat.

The extreme heat causes some of the sand and clay to become sintered, that is to say agglomerated in large masses which are, therefore, easier to remove than smaller pieces. where ash melting point is low.

Alternately, the solids may be removed as slag Solid particles are removed from the high temperature burner and introduced into a cooler. The heat liberated during this cooling process is captured in a boiler and may be used for production of steam.

The advantages of this invention in relation to conventional fluid coking may be summarized as follows:

The mineral solids from the tar sands .are coated with coke in the first stage coking reactor. In the case of a froth from an Athabasca sand, this protective coke covering on the solid particles eliminates problems of erosion of apparatus and entrainment of fine solid particles, which would otherwise be encountered if all the carbon were burned off the solids in a conventional fluid coker burner. The principle of operation of the burner is that at least 5% and preferably 50% of coke is maintained on the solids to produce a protective coveri-ng during burning in the burner. If necessary, in cases where the heat load is unusually high in the reactor, supplementary fuel such as torch oil is burned in the burner in preference to the coke covering to maintain this protective coating.

The iirst coking reactor operates at low severity without recycle of oil except as slurry recycled to return solids to the reactor. Presence of water in the feed makes it possible to reduce cracking time. This maximizes the liquid oil product yields, particularly where the feed stock contains a large amount of low boiling hydrocarbons.

Catalytic fines are regenerated and used as a catalyst in the cracking reactor. The presence of these fines will increase the dry gas and naphtha yield and decrease the gas oil within the reactor.

The second stage coker operates on the unconverted residuum or residual oil from lthe first stage. As mentioned previously, this residuum may be subjected to a great variety of treatment as for example visbreaking. This coker is of the conventional type and employs recycle of unconverted residuum. Recycle rates would be undesirably high if recycle were attempted in the first stage coker. This is because of the high steam dilution rate caused by the water in the feed. Also, the second stage coker makes high quality coke since the oil feed is relatively free of solids such as sand, clay, etc. In fact, where there is excessive entrainment of solids in the vaporous product from the first stage coker reaction, it is possible to employ a solids settling step with recycle of solids to the first stage reactor and the passing of a solids-free oil feed to the second stage coking reactor.

Since it is desirable to recover the heating value of the protective coke layer on the sand or other solids, this is done more efficiently than with a conventional uid coker burner. The solids leaving the first stage burner .are completely burned at high temperature and high velocity in a subsequent high temperature transfer line or cyclone-type burner where carbon or coke is burned almost entirely to carbon dioxide. This also permits complete removal of the carbon rather than the incomplete removal which would be experienced in a conventional uid burner. The heat in the ue gas containing carbon dioxide and the solids from the high temperature burner is recovered by producing steam in boilers. In the process of removing carbon, some of the fine particles of clay are activated and regenerated to form catalyst for use in this first stage coker.

In the drawing, the figure is a schematic representation of a preferred embodiment of this invention.

The reference numeral designates a line through which a froth, which is obtained from a tar sand and is an admixture of oil, sand, mineral solids such as clay, water and air, is introduced into a fluid coker unit including a reactor 11 and a burner 15. The froth feed is preheated in heater 11'.

Reactor 11 is maintained at a temperature between 800 F. and 1200 F. which is the conventional temperature of a fluid coker. The bed contains a sticky bed of uid coke particles which may range in size between 20-400 microns. Pressure may be maintained between 5 and 15 p.s.i.g. and preferably at about 10 p.s.i.g. Superficial velocity of gas passing up through reactor 11 may be between 1 and 4 feet per second and the solids bed depth, which may vary widely, should be about 30 to 50 feet. The fluidized bed 28 is maintained as such by the upflowin'g hydrocarbon gases and vapors formed by the coking of the oil feed and by steam added to the process through line 10. When using finely divided coke of about 20-400 microns .and at a superficial velocity as above mentioned the density of the fluidized bed 28 will be about 35 lbs. per cu. ft. depending on the superficial gas Velocity selected and the particular particle size range. Catalytic fines are added to the reactor 11 from catalyst regenerator 65 through lines 75', 76 and line 10.

Burner 15 is maintained at a temperature of 900 F. to l200 F. Pressure may vary between 5 and l5 p.s.i.g. with about 10 p.s.i.g. ybeing preferred. Superficial velocity of the gas passing up through burner 15 may be between l-3 ft./sec. and bed depth should be between 10 and 30 ft. Air to maintain combustion is added to the bottom of the burner 15 through line 16. Cyclones 17 and 18 are in series and are located outside burner 15 and they serve to separate solid particles from flue gases in which they are entrained. Part of these solid particles is returned to bed 21 through diplegs 19 and 20 and line 19. The amount of solids flowing from diplegs 19 and 20 into line 19 may be independently controlled by providing separate lines and valves (not shown). Part of the particles pass to burner 52 through lines 61, 60 and 51 where all the carbon is removed and a third portion passes to catalyst regenerator 65 through lines 61, 62 and 64 from whence fine material passes from regenerator 5 through lines 76 and 10 to recator 11. The particles are heated in the regenerator 65 and the carbon is burned off. Thus the catalytic clay particles are regenerated. It should be noted that the catalytic characteristics of clay particles are known. Hot coke particles are removed from the burner 15 through line or standpipe 22. They pass through slide valve 23 and then re-enter reactor 11 through riser 24. Particles are mixed with steam introduced through line 25 and the mixture passed through riser 24. In order not to burn all the coke off the solids and to maintain at least 5 to 50% of the coke on the solids in the burner it may be necessary to add supplementary fuel to the burner; this fuel may be added through line 26. Many different fuels are acceptable and gas, torch oil or gas oil are among several which may be utilized. Alternatively, hot combustion products from line 53 may be passed through burner 15 to supply heat (by means not shown).

The oil within the froth collects on the coke particles in the bed 28 of reactor 11 and most of the solid materials and especially the fines adhere to the surface of the coke particles. The hydrocarbon oil is cracked and vaporized. The vaporous products move upwardly in the bed and into the space above the @bed and pass through cyclone separator 27. Here some of the solids entrained within the vaporous products are separated and returned to bed 28 through dipleg 29. The vapors pass up into scrubber 29. Scrubber 29 is superimposed on the reactor 11 and includes fractionator 30. Within the scrubber, dust particles and other impurities are removed; the clean vapors then pass up to fractionator 30. Here they are separated into a multiplicity of hydrocarbon fractions. Heat is removed from scrubber 29 and fractionator 20 by conventional heat exchange (not shown).

The lightest fraction boiling up to 500 F. is removed through line 31. It is passed through heat exchanger 32 through line 32 and is introduced into separator 33 from whence gaseous products are withdrawn overhead through line 34 and liquid products through line 35.

The middle fraction boiling at 400 F. to 950 F. comprises gas oil and is drawn off through line 36.

The heaviest fraction, boiling in excess of 950 F., is withdrawn from the bottom of fractionator 30 through line 37. If desired or necessary, it may be passed to clarifier alternate 38 through line 41 for removal of solid materials. From clarifier 38 the heavy fraction may be returned to line 37 through line 39 or optionally it may be returned to reactor 11 through line 40. If the heavy fraction is returned to reactor 11 it will contain the heavy metals which are separated within clarifier 38. This heaviest fraction may be directed into line 26 and used as supplementary fuel for burner 15.

The heavy fraction is directed through line 37 to a conventional fiuid coker 42. Here ordinary iiuid coking conditions are utilized, i.e. 900 F. to 1400 F. in the reactor and 1000 F. to l600 F. in the burner. The usual products are recovered from Coker 42. Naphtha is recovered through line 43, a 430 F. to 650 F. heating oil cut is recovered through line 44, and a gas oil boiling between 650 to 1000 F. is recovered through line 45.

Furthermore, a high value coke is recovered through line 42. Most of the impurities are retained in reactor 11 and consequently this coke from coker 42 is exceptionally good. It contains virtually no nickel and vanadium although some sulfur remains. Consequently, this coke product is suitable for use in electrodes and as metallurgical coke.

Returning to reactor 11 and burner 15, which comprise the first coking unit, reactor 11 is maintained at a te'mperature between 800-1100 F., preferably at about 875 F. Pressure may be maintained between 5-15 p.s.i.g. and preferably at about p.s.i.g. Superficial gas Velocity within the reactor may be between 1 and 4 feet per sec ond and bed depth should be kept at 30-50` feet. Coke particle size may vary between 20 and 400 microns. The liuidized bed 28 is maintained as such by the upflowing hydrocarbon gases and vapors formed by the coking pf the oil feed and by steam added to the process through ine 10'.

When using finely divided coke of about 20 to 400 microns and at a superficial velocity, as above mentioned, the density of the uidized bed will -be about 35 lbs. per cu. ft. but may vary between about and 60 lbs. per cu. ft., depending on the gas velocity selected and the particular particle size range. Particles are removed from reactor 11 and directed to burner 1S through standpipe 46, slide valve 47 and riser 48. The particles are passed through line 48 in admixture with air or other gas supplied through line 15'.

Burner 15 may be maintained at a temperature between 900 and 1200 F., preferably at about 1000 F. Pressure may vary between 5 and 15 p.s.i.g. with about l0 p.s.i.g. being preferred. The upflowing gas velocity in the burner 15 may be between 1-3 ft./sec. and bed depth between 10-30 feet. About 5-50% of the coke deposited on the solids is not burned and remains adhered to the solids in the burner 15.

Gas entrained coke or carbon covered solids are removed overhead from the burner 15 through line 16. These solids first pass through cyclone separator 17 where some of the solids are removed and returned through dipleg 19. The remaining gas entrained solids pass into cyclone 18 through line 17. Here further cyclone separation of solids is made; gases are released to the stack through line 18', solids are removed through dipleg 20. A portion of the tine and coarse solids is passed through line 19 back into burner 15. Another portion of the fine and coarse solids is passed into line 61, material from line 61 may be passed through line 60 into line 51 and Ithen to burner 52. Fine and coarsematerial within line 61 may be passed through line 62, valve 63 and then to line 64 from whence they are passed to the regenerator 65. Boiler 65 serves to recover excess heat from regenerator 65.

The regenerator is of the fluid bed variety and is maintained at a temperature of 1100-1500 F. and a superiicial gas velocity of 144 ft./sec. Air is added to regenerator 65 through line 66. Gas entrained solids are removed through line 66. They pass through cyclone separator 67, solids are removed through dipleg 68. The remaining gas entrained solids pass through line 69 into second cyclone separator 70. Gases are directed from cyclone separator 70 to burner 15 through line 71. The separated solids from separator 70 pass through dipleg 72 into line 73, solids from dipleg 68 also pass into line 73. The solids may pass through valve 74 back to catalyst regenerator 65. Or, they may pass through line 75 into line 76. These fine and coarse solids have been subjected to catalyst regeneration and, therefore, have lost their carbon or coke coating. Other fine and coarse material is removed from regenerator 65 through line 75. The line and coarse material is passed from line 76 into line 10 and from there to reactor 11. In reactor 11 the fines have a catalytic effect and increase the naphtha yield of the Coker. If desired, only tine material may be passed into line 10. This may be done in a variety of ways, for example a screen to remove coarse materials may be placed at any point on line 76.

Carbon or coke coated solids are removed from the dense bed 21 in burner 15 through line 50, and must pass through valve 50. Coarse coated material passes through line 51 into high temperature short-time burner 52. Air for the burner is supplied through line 51. Coated materials from line 50 pass into line 64 from whence they are transported to regenerator 65.

Burner 52 may be either a fluid bed, a cyclone type or transfer line. The carbon-coated solids are retained in burner 51 for about .1 to 10 seconds at a temperature of between 1500 and 3000 F., preferably about 2500 F.

The temperature in burner 52 is suiciently high and suicient air is added through line 51 to burn all of the coke on the solid particles to carbon dioxide. As a result great amounts of heat are liberated, as much as 5,000 to 10,000 B.t.u. per pound of solids. Sufficient heat is liberated to cause sintering or slagging of the solid particles. Sintered particles may range in size from 20 to 1000 microns. The hot ue gas containing carbon dioxide is removed overhead through line 53 and passed through boiler 54 where the heat is recovered to produce steam; the steam may be utilized for any conventional purpose. The steam may be fed to reactor 11 through line 10 or into riser 24 through line 25. Fine particles leaving boiler 54 are collected in a cyclone (not shown) and are electrostatically precipitated to prevent air pollution. Alternatively, they may be recycled to reactor 11 for use as catalytic material.

The mineral solids, sorne of which are sintered from the high temperature resulting from burning the coke to carbon dioxide in burner 52, are removed through line 54 and are introduced into fluid bed cooler 55. Heat from the solid particles within the cooler is captured within boiler 55. Heat in the amount of 100 to 500 B.t.u. per pound of solids is liberated. This heat may also be utilized for process steam by directing it to line 10.

Sand and clay representing 70 to 99% of that found in the original feed are removed through line 56 and discarded.

In a specific embodiment of this invention, 10,000 barrels a day (deaerated basis) of froth were utilized. The froth is obtained by a froth otation process; Athabasca tar sand is contacted with hot water. The aqueous layer is removed; this liquid is in the form of a froth due to trapped air and gases. The froth which is an admixture of 2O wt. percent Water, 70 wt. percent crude oil, 5 wt. percent sand, and 5 wt. percent clay, the solids being 50 wt. percent of ne materials (less than 10 microns), and 30 vol. percent gas, is introduced into reactor 11 through line 10.

Reactor 11 is maintained at a temperature of 900 F. and a pressure of 30 p.s.i.g. Superficial gas velocity is Jabout 3 ft./sec. for maintaining the uidized bed 28 of 7 solids. The bed depth is maintained at 40 feet. In the reactor 11 the oil in the tar feed is cracked and forms vaporous products, The vapors pass through cyclone 27 and entrained solids are returned to bed 28 through dipleg 29'. Vapors pass up through scrubber 29 and uncondensed vapors pass to fractionator 30. In the scrubber heavy ends are condensed and entrained fines scrubbed out of the vaporous products.

The vapors are separated into three fractions in the scrubber and fractionator 30. The heaviest, or 950 F. fraction, is drawn off through line 37 and comprises about 1500 b./d. This fraction is directed into conventional fluid coker 42; about 60 tons a day of high value coke are recovered through line 42. The coke contains:

(l) Vanadium--less than 100 parts per million (2) Nickelless than 50 parts per million (3) Sulfur-4% A middle fraction boiling at SOO-950 F. is recovered through line 36 as gas oil. This fraction accounts for about 2000 b./\d. of product.

The light fractions boiling at up to 500 F. are drawn off through line 31 this constitutes about 2500 b./ d. This fraction passes through heat exchanger 32 and into separator 33 from whence it is separated into gas and liquid product.

The solids in lbed 28 are coated with coke during coking in reactor 11 and the solids -are drawn olf through standpipe 46, pass through valve 47 and through line 48 into burner 15. The burner is maintained at ya temperature of 1000 F. and a pressure of 10 p.s.i.g. Coke coats the solid material and, about -50% of the coke is not burned. Flue gases pass through cyclones 17 and 18 outside of burner 15; solid material entrained within the gases is returned to bed 21 from diplegs 19 and 20 and line 19. Alternatively, the solids may pass through line 61, line 62, valve 63 and line 64 thereby entering catalyst regenerator 65. Additional coke coated solids leave burner 1S, pass through line 50, valve 50' then into line 64 and finally pass to regenerator 65. To prevent all of the coke coating from being burned off the particles, torch oil in the amount of 300 b./d. is added to burner through line 26.

Catalyst regenerator 65 operates at a temperature of about 1200 F. and a superficial gas velocity of 2 ft./sec. It is a fluid regenerator; hot gases from the regenerator pass through cyclones 67 and 70 whereby entrained lines are separated. The clean gas is then passed through line 71 into burner 15 thereby supplying heat for the burner. About 150 tons a day of solids from regenerator 65 pass through lines 75', 76 and into line 10 from whence they are passed to reactor 11.

Coarse carbon-coated solids are withdrawn from burner 15 through lines 50 and `51 and are introduced into cyclone type burner 52. This burner is maintained at a temperature of about 2500 F. The solids are kept there for `about l second at which time approximately 95% of the coke is burned to carbon dioxide thereby generating about 100 million B.t.u./hour of heat. Simultaneously, about 80% of the solid material is sintered into particles of about to 1000 microns diameter.

The hot flue gases are withdrawn through line 53 and pass to boiler 54. Boiler 54 contains a polution control device such -as a fly ash separator (not shown).

Hot solid particles are withdrawn from burner 52 through line 54 and directed to cooler 55. After cooling to a temperature of about 500 F., the sand and clay particles are withdrawn through line 56. About 120 tons/ day of solid material are withdrawn; this represents about 80% of the solid material found in the original tar mixture introduced into reactor 11 and includes about 75% of the fine material. About 5 million B.t.u./hour of heat are captured within boiler 55'. This is heat liberated by the cooling solids.

It should be noted that this invention may also be utilized for recovery of oil from shale as well as the underground recovery of bitumen.

What is claimed is:

1. A process for recovering oil from a froth obtained from tar sand and containing oil, mineral solid particles and water which comprises introducing said froth into a low severity coking Zone maintained at a temperature between about 800 F. and 900 F. wherein it is contacted with a fluidized dense turbulent bed of hot cokecontaining mineral solid particles to remove oil and water and to convert oil to vapors and coke is deposited on the solid mineral particles to form a protective coke covering on said solid mineral particles, removing converted vapors from said coking zone, removing a portion of the said coke-containing solid particles to a first burning zone maintained at a temperature between about 900 F. and 1200 F. to increase the temperature of the said coke-containing particles, adding supplementary fuel to said first burning zone to supply additional heat thereto and so as to burn a portion only of said coke on said mineral solid particles, returning a portion of said heated coke-containing mineral solid particles to said coking zone, removing another portion of said heated cokecontaining mineral solids from -said burning zone to a second high temperature short time burning zone maintained at a higher temperature of 1500 to 3000 F., wherein the coke on said coke-containing mineral solid particles is substantially all burned to carbon dioxide to produce hot flue gas and hot mineral solids, recovering heat from said hot flue gas, passing hot mineral solids from said second burning zone to a cooling zone to recover heat therefrom and then discarding said mineral solids.

2. In a process for recovering oil from froth obtained from tar sand and comprising a mixture of oil, water and mineral solids, the steps which comprise introducing said froth into a low severity coking z-one wherein it is contacted with a fluidized dense turbulent bed of hot coke-containing mineral solid particles to remove water and oil and to convert the oil to lower boiling hydrocarbons, fractionating the hydrocarbons into a light stream boiling up to about 500 F., a middle boiling stream boiling between about 400 and 950 F. and a heavy 950 F.l fraction, passing said heavy fraction to a second fluid coking unit to produce gas and liquid hydrocarbon products and a high value coke, depositing coke on the said mineral solid particles in said first coking zone, removing a portion of the said coke-containing mineral solid particles `and passing them to a first burning zone to increase the temperature of the said mineral solid particles, adding supplementary fuel to said first burning zone so that between about 5 to 50% of the coke on said coke-containing mineral solids remains unburned, passing a portion of said heated coke-containing mineral particles back to said first coking zone, passing .another portion of said heated coke-containing mineral particles from said first burning zone to a high temperature short time second burner zone maintained at a higher temperature between about 1500 to 3000" F. to burn substantially all the said coke on said coke-containing mineral particles to carbon dioxide to produce hot flue gas and hot mineral solids, removing said hot flue gas overhead and recovering heat therefrom, passing said hot mineral solids to a cooling zone to recover heat therefrom and then discarding said cooled mineral solids.

3. The process of claim 2 where the supplementary fuel is at least a portion of said heavy 950 F.'-l stream.

4. The process of claim 2 where said heavy oil fraction is introduced into a clarifier before passing to said second fiuid coker to remove solids from said heavy oil fraction.

5. A process for recovering oil from a froth obtained from tar sand and containing oil, mineral solid particles including fine sand and clay particles of less than 10 microns and water, which comprises introducing said froth into a low severity ooking zone maintained at a temperature between about 800 F. and 900 F. wherein it is contacted with a fluidized dense turbulent bed of hot coke-containing mineral solid particles to remove oil and water and to convert oil to vapors and coke is deposited on the solid mineral particles to form a protective coke covering on said solid mineral particles and to cause line mineral solid particles to stick to larger particles having a cohesive layer of coke and to thereby maintain said line particles in solid reactor, removing converted vapors from said coking zone, removing a portion of the said coke-containing solid particles to a first burning zone maintained at a temperature between about 900 F. and 1200 F. to increase the temperature of the said coke-containing particles, adding supplementary fuel to said first burning zone to supply additional heat thereto 'and so as to burn la portion only of said coke on said mineral solid particles, returning a portion of said heated coke-containing mineral solid particles to said coking zone, removing another portion of said heated coke-containing mineral solids from said burning zone to `a second high temperature short time .burning zone maintained at a higher temperature of about 1500D F. to 3000o F., wherein the coke on said coke-containing mineral solid particles is substantially all burned to carbon dioxide to produce high temperature ue gas .and hot References Cited by the Examiner UNITED STATES PATENTS 2,480,670 8/1949 Peck 208-11 2,905,595 9/1959 yBerg 208-11 3,093,571 6/1963 Fish et al. 208-11 3,167,494 1/1965 Crawford 208-11 FOREIGN PATENTS 469,711 8/1944 Canada.

OTHER REFERENCES The Blair Report, 1950, published by the Government of the Province of Alberta, pp. 59 to 80.

DANIEL E. WYMAN, Primary Examiner.

ALPHONSO D. SULLIVAN, Examiner.

H. LEVINE, P. KONOPKA, Assistant Examiners. 

2. IN A PROCESS FOR RECOVERING OIL FROM FROTH OBTAINED FROM TAR SAND AND COMPRISING A MIXTURE OF OIL, WATER AND MINERAL SOLIDS, THE STEPS WHICH COMPRISE INTRODUCING SAID FROTH INTO A LOW SEVERITY COKING ZONE WHEREIN IT IS CONTACTED WITH A FLUIDIZED DENSE TURBULENT BED OF HOT COKE-CONTAINING MINERAL SOLID PARTICLES TO REMOVE WATER AND OIL AND TO CONVERT THE OIL TO LOWER BOILING HYDROCARBONS, FRACTIONATING THE HYDROCARBONS INTO A LIGHT STREAM BOILING UP TO ABOUT 500*F., A MIDDLE BOILING STREAM BOILING BETWEEN ABOUT 400 AND 950*F. AND A HEAVY 950* F.+ FRACTION, PASSING SAID HEAVY FRACTION TO A SECOND FLUID COKING UNIT TO PRODUCE GAS AND LIQUID HYDROCARBON PRODUCTS AND A HIGH VALUE COKE, DEPOSITING COKE ON THE SAID MINERAL SOLID PARTICLES IN SAID FIRST COKING ZONE, REMOVING A PORTION OF THE SAID COKE-CONTAINING MINERAL SOLID PARTICLES AND PASSING THEM TO A FIRST BURNING ZONE TO INCREASE THE TEMPERATURE OF THE SAID MINERAL SOLID PARTICLES, ADDING SUPPLEMENTARY FUEL TO SAID FIRST BURNING ZONE SO THAT BETWEEN ABOUT 5 TO 50% OF THE COKE ON SAID COKE-CONTAINING MINERAL SOLIDS REMAINS UNBURNED, PASSING A PORTION OF SAID HEATED COKE-CONTAINING MINERAL PARTICLES BACK TO SAID FIRST COKING ZONE, PASSING ANOTHER PORTION OF SAID HEATED COKE-CONTAINING MINERAL PARTICLES FROM SAID FIRST BURNING ZONE TO A HIGH TEMPERATURE SHORT TIME SECOND BURNER ZONE MAINTAINED AT A HIGHER TEMPERATURE BETWEEN ABOUT 1500 TO 3000*F. TO BURN SUBSTANTIALLY ALL THE SAID COKE ON SAID COKE-CONTAINING MINERAL PARTICLES TO CARBON DIOXIDE TO PRODUCE HOT FLUE GAS AND HOT MINERAL SOLIDS, REMOVING SAID HOT FLUE GAS OVERHEAD AND RECOVERING HEAT THEREFROM, PASSING SAID HOT MINERAL SOLIDS TO A COOLING ZONE TO RECOVER HEAT THEREFROM AND THEN DISCARDING SAID COOLED MINERAL SOLIDS. 